Step-path failure mechanism and stability analysis of water-bearing rock slopes based on particle flow simulation

Abstract

Step-path failure is a typical damage mode of rock slope featuring intermittent joints. In order to investigate the effect of water-fracture interaction on the stepped failure, laboratory experiments of rock materials and numerical simulation of slopes with intermittent joints were conducted. At the laboratory scale, the influence of water-fracture interaction on the mechanical characteristics and acoustic emission response of step-path failure in rocks was examined, and the particle flow model parameters were calibrated for uniaxial testing. At the field scale, the step-path failure process of the rock slope near Longmenqiao reservoir was numerically analyzed using the particle flow method to assess the effects of water and joint distribution on failure. Laboratory findings suggest that compared with dry red sandstone, the average uniaxial compressive strength and average elastic modulus of saturated red sandstone decrease by 35.82% and 23.33%, respectively. The increase in fissure angle in sandstone results in enhanced strength and stiffness, alongside a transition from shear to tension failure mode, with a delayed occurrence of large-scale acoustic emission events. In particular, within the 30°–60° range, the uniaxial compressive strength and elastic modulus of saturated sandstone increase by 66.78% and 29.64%, respectively. The analysis of crack propagation and stress field during slope deformation shows that step-path failure is a progressive process from bottom to top, and revealed the control mechanism of joint and bridge angle on slope stability. The research results enhance the understanding of the step-path failure mechanism and provide important theoretical support for the stability evaluation and landslide monitoring of rock slopes with intermittent joints.